1. Field
Embodiments of the invention relate to a flexible solid electrolyte, an all-solid-state lithium battery including the flexible solid electrolyte, and a method of preparing the flexible solid electrolyte.
2. Description of the Related Art
Lithium batteries typically have high voltage and high energy densities, and thus are used in various applications. Devices such as electric vehicles, e.g., a hybrid electric vehicle (“HEV”), plug-in hybrid electric vehicle (“PHEV”) and the like, are desired to be operable at high temperatures, to charge or discharge a large quantity of electricity, and to have long-term usability, such that such devices use lithium batteries having high-discharge capacities and better lifetime characteristics.
A lithium battery using liquid electrolyte including a lithium salt dissolved in an organic solvent may be chemically unstable when using an electrode operating at a high voltage of about 5 volts (V) or greater. In such a lithium battery, the liquid electrolyte may begin to decompose at a voltage of about 2.5 V or greater, and a leakage may occur such that a risk of fire or explosion may be high. Growth potential of dendrite from the liquid electrolyte may lead to self-discharge or overheating of the lithium battery.
All-solid-state liquid batteries using a solid electrolyte as a lithium ion conductor are considered relatively stable compared to lithium batteries using liquid electrolytes. Unlike lithium batteries using liquid electrolytes, all-solid-state lithium batteries have no leakage concerns, and thus may be very safe and have high stability. However, electrolyte materials for the all-solid-state lithium batteries are inherently brittle and not flexible such that the solid electrolyte may decompose when used along with a lithium anode or a high-voltage electrode, and ionic conductivity of the solid electrolyte may be low due to a high grain boundary resistance.